With most internal combustion engines available today there is a disadvantage in that any liquid fuel droplets not vaporized in the primary fuel vaporization means of the engine, e.g. the carburetor or fuel injection nozzle, are either deposited on the walls of the inlet tract or carried into the combustion chamber in droplets form. If deposited on the walls of the inlet tract, this fuel is eventually vaporized on contact with the heated portion of the inlet tract which causes considerable enrichment of the mixture leading to incomplete combustion within the combustion chamber of the engine causing high pollutant discharge in the exhaust from the engine. If the droplets are carried into the combustion chamber, the interior portion of the droplet is not so readily burned as the exterior portion thereof so causing incomplete combustion within the combustion chamber of the engine and resultant high pollutant emissions. These disadvantages are particularly apparent during periods of de-acceleration or idling when high vacuums are experienced in the inlet manifold.